Question

52 year-old male with diabetes complains of severe left foot pain for one month and now inability to ambulate. Vital signs are normal and X-rays are shown below. What's the diagnosis and why should you get a biopsy early?  

 

Answer

Answer: Osteomyelitis and a bone biopsy (with culture) should be obtained early and before starting antibiotics.

Osteomyelitis is inflammation of a bone secondary to an infecting organism.

Risk factors include:

• Injury to bone from surgery or trauma
• Spread via bacteremia or overlying skin infection
• Secondary to foreign body or prosthetics

Causative bacteria typically include S. Aureus, Pseudomonas, Salmonella (classically with Sickle cell)

Diagnosis

• X-ray may be used (periosteal or cortical changes) but lacks sensitivity; abnormalities may not be evident for up to 14 days
• Bone scan is a better test, but false positives may occur with overlying skin infections
• MRI is arguably the best test; delineates tissues planes and the extent of infection 

Early and long-term antibiotic treatment (4-6 weeks) is required, but should be done AFTER obtaining bone biopsy and culture; long-term antibiotics are the rule and the most narrow spectrum antibiotic should be determined.

Operative management is sometimes required; especially if secondary to infected prosthetics.

References

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